<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
		<style>
			.box1{
				width: 200px;
				height: 200px;
				background-color: #BBFFAA;
				float:left ;
				/*overflow：hidden;*/  /*为父元素开启BFC,子元素和父元素外边距不会重叠*/
			}
			
			.box2{
				width: 200px;
				height: 200px;
				background-color: pink;
			/*	overflow: hidden;*/  /*为box2开启BFC，开启后元素不会被浮动的元素覆盖*/
					
			}
			
			.box3{
				width: 100px;
				height: 100px;
				background-color: orange;
				margin-top: 100px;
			}
		</style>
	</head>
	<body>
		<div class="box1">
			<div class="box3"></div>
		</div>
		<div class="box2"></div>
	</body>
</html>
